A redox enzyme is frequently used for synthesizing a fine chemical product, medicine and medical supplies, food additives, herbicides, or the like, which has an industrial high value. The redox enzyme requires a coenzyme such as nicotinamide adenine dinucleotide (including a reduced type and phosphate, that is, NAD(H) and NADP(H)) to have activity. A coenzyme is a low-molecular substance and an essential material for an enzyme reaction. Especially, a pyridine-based coenzyme is widely used. A reaction using the redox enzyme requires a continuous supply of coenzyme to produce a product, but there is a problem in that the cost of the coenzyme is very high. In order to solve the aforementioned problem, many researchers are studying on a regeneration of a coenzyme, and also on methods for effectively using the coenzyme by finding residues in relation to coenzyme specificity.
Recently, uses of L-carbohydrates and nucleoside derivatives thereof are dramatically on the increase in a medical field. Especially, some modified nucleosides exhibit a considerable potential as a useful antiviral agent. L-ribose is an important core pentose constituting a frame for synthesizing L-ribonucleoside, L-oligoribonucleoside, and many other treating agents. Since L-nucleoside has high stability from an attack of nucleases in the body as compared with D-nucleoside, L-nucleoside is a candidate substance having high potential in being used as a material for treating. Since L-ribose is known to have high usefulness as a production raw material that is the basis of medicine and medical supplies, such as an antiviral agent and anticancer drug, L-ribose has been noticed in recent years and thereby establishment of high efficiency biological production method of L-ribose is required.
Despite the aforementioned importance and usefulness, unlike D-ribose, L-ribose is present in a small quantity over the natural world, and also even though a method for producing L-ribose is known, a relatively high cost ($1,000/kg) is required. Accordingly, there is a need for a method that is capable of commercially producing L-ribose at low cost.
Some chemical methods for converting L-arabinose, D-glucose, L-xylose, D-galactose, and D-ribose into L-ribose derivatives are known (Matteson, D. S, and Peterson, M. L. (1987) J. Org. Chem., 52(23), 5116-5121; Yamaguchi, M. and Mukaiyama, T. (1981) Chem. Lett., 7, 1005-1008). However, the methods have disadvantages, such as low yield, needs for a high-priced starting material, many reaction steps, difficulty of mass synthesis, and the like. In addition, the methods take long-period time due to a series of chemical reactions; require relatively high-priced chemicals; generate unnecessary by-products; and are labor intensive methods. Accordingly, an attempt for biochemically producing L-ribose from L-ribulose using a microorganism and an enzyme thereof has been made (Shimonishi, T., Izumori, K., J. (1996) J. Ferment. Bioeng. 81, 493-497). It is expected that the above disadvantage can be overcome by using an enzymatic production method for producing L-ribose using the biocatalizer described above.
Korean Patent Publication No. 1020090081435, a relevant prior patent, relates to “a thermal resistance L-ribose isomerase and a method for producing the same,” in which the thermal resistance L-ribose isomerase acts as a production of L-ribulose by isomerizing L-ribose having a molecular weight of 32,000 (SDS-PAGE), the optimum temperature of 45° C., the optimum pH of 9.0 (glycine-NaOH buffer solution), and a stable physicochemical property of temperature stability to 45° C. upon being thermal-treated for 10 minutes at pH 9.0, or inversely as a production of L-ribose by isomerizing L-ribulose. In addition, the above Korean Patent Publication No. 1020090081435 discloses a conversion method of aldose and ketose, in which a thermal resistance L-ribose isomerase that is an enzyme derived from Raoultella ornithinolytica MB426 (NITE BP-277) is reacted with the aldose selected from L-ribose, D-lyxose, D-talose, D-mannose, L-allose, and L-gulose, thereby isomerizing the aldose and then producing the ketose selected from the corresponding L-ribulose, D-xylulose, D-tagatose, D-fructose, L-fucose, and L-sorbose, respectively or the L-ribose isomerase is reacted with the ketose selected from L-ribulose, D-xylulose, D-tagatose, D-fructose, L-fucose, and L-sorbose, thereby isomerizing the ketose and then producing the aldose selected from the corresponding L-ribose, D-lyxose, D-talose, D-mannose, L-allose, and L-gulose, respectively.
Korean Patent Publication No. 1020100053294, a relevant prior patent, relates to “a novel L-arabinose isomerase and a method for producing L-ribulose using the same,” and more particularly, to L-arabinose isomerase expressed from a gene of a novel L-arabinose isomerase derived from Bacillus licheniformis strain having arabinose isomerase activity, a method for producing L-arabinose isomerase from the strain transformed by a recombinant expression vector including the above gene, and a method for producing L-ribulose using the above enzyme.